In connecting transmission cables of the type buried underground, and referred to as direct burial cables, an installer is usually faced with the problem of trying to connect cable of various construction. Typically, these cables contain a plurality of insulated conductors surrounded by an insulated thermoplastic sheet and a metallic conductive sheath which may or may not be itself insulated. An outer insulative jacket usually surrounds the entire cable structure. In various applications, these cables may vary as to the size and number of conductors, composition and construction of the metallic sheath and thickness of the outer jacket. Furthermore, most cables of this type often include a material core which fills the void between the conductors inside the conductive sheath. This core may range from a core constructed of a solid insulative material to one of relatively viscous petroleum gel which is injected between conductors. It is apparent that due to these construction variations, each type of cable will be subject to different degrees of deformation both upon interconnection and long term creep. It is not uncommon for many of the cable structures to deform from a normally circular cross-section to one that is more elliptical or flattened.
The actual interconnection of the signal carrying conductors of two or more cables is accomplished in one of a number of well-known methods. However, in addition to connecting these signal-carrying conductors, the conductive ground sheaths must also be connected to insure ground continuity between the cables.
The art has seen a number of interconnection techniques for connecting the ground sheath of two direct burial transmission cables. One such method employs a split bolt or nut to clamp the conductive sheath of two stripped cables. Another, described in a paper by David Lane and Bob Young entitled, "Sheath Bonding Terminal for Buried Service Wire, International Wire & Cable Symposium Proceeding" (1982), employs a clip "type" spring contact for engaging the stripped cable sheaths. In each of the prior methods, the cable would have to be previously stripped or "skinned" before the connector could be employed. Stripping a cable is both time-consuming and difficult as, in addition to stripping away the outer insulative jacket, the conductive sheat often contains a further insulative coating which is exceedingly difficult to remove. Failure to sufficiently remove the coating will result in an ineffective ground connection.
There are still other connectors known in the art employing insulation piercing techniques for piercing the insulation of a cable and contacting the conductive member. Such an insulation piercing connector is shown and described in U.S. Pat. No. 4,293,176 issued Oct. 6, 1981 to Lindlof. However, connectors of this type could not be employed with transmission cable for contacting the conductive sheath, as depth of penetration cannot be precisely regulated. Overpenetration could cause a piercing of the conductive sheath and contact with a signal-carrying conductor thereby causing a short. Conversely, underpenetration would provide ineffective ground connection. Further, as the cable may exhibit some degree of "creep" due to stresses applied to the plastic elements by the connector, the insulation displacing contacts which were initially suitably connected may become dislodged from the sheath and fail to provide a continuous and reliable ground connection.
It is therefore desirable to provide an insulation piercing cable connector which is capable of receiving a wide variety of cable constructions and where the piercing force can be precisely regulated to prevent over or under insertion. Further, the connector should be able to compensate for cable creep throughout its life.